Broadly, this invention relates to a process for encapsulating particulate materials within copper metal to produce copper coated composite particles suitable for use in fabricating filled copper structures. More specifically, the invention is directed to a process for encapsulating boron carbide particles within electrodeposited copper of high density. The primary use for such particles is the fabrication of containers designed for storage, disposal, or transportation of nuclear waste materials and other radioactive, radiation emitting (e.g., neutron emitting) substances.
One of the known containers for housing neutron-emitting nuclear waste materials comprise a solid aluminum mass containing a plurality of baskets for containing the waste material. Each basket is lined with boron carbide (B.sub.4 C) filled copper plates. Copper is the metal of choice because of its high specific heat high thermal conductivity and high melting point. Boron carbide is used as a filler because it is characterized by a high capture cross section for neutrons.
The ideal boron carbide filled copper plate material for use in fabricating these and other types of containers designed for housing nuclear wastes would be a substantially pure, dense, matrix of copper metal, tightly bonded to a uniformly dispersed boron carbide phase consisting of a multiplicity of carbide particles arranged within the copper matrix such that no straight line passing through the plate fails to impinge upon a boron carbide particle. A high loading of boron carbide plus a uniformly dispersed copper phase are thus desirable. This can be achieved most readily by the electroplating process described in this invention.